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目的探讨直肠癌患者术前体素内不相干运动(IVIM)磁共振成像中不同感兴趣区(ROI)选择方法对参数测量准确性的影响。方法病理诊断为直肠腺癌患者43例,术前行盆腔常规磁共振扫描和IVIM检查。在b=1000s/mm2的IVIM原始图像上采用三层法和单层法勾画ROI获得IVIM参数值:纯扩散系数(D)值,灌注分数(f)值,灌注相关假扩散系数(D*)值。比较2种ROI勾画法之间以及其与正常肠壁的参数值之间的差异;采用ROC曲线分析ROI勾画法测得的参数值与正常肠壁的区分效能。结果三层法和单层法勾画直肠癌病灶ROI测得的D值、f值和D*值差异均无统计学意义(P>0.05)。与正常肠壁比较,三层法和单层法勾画直肠癌病灶ROI测得的D值均较低(P<0.05);单层法勾画直肠癌病灶测得的f值亦较低(P<0.05)。三层法的诊断准确性和特异度更高。结论直肠癌病灶采用三层法和单层法勾画ROI得出的IVIM各参数间无显著差异;采用三层法得到的病灶数据与正常肠壁区分度更高。
Objective To investigate the influence of different ROI methods on the accuracy of parameter measurement in preoperative patients with unrelated voxel movement (IVIM) magnetic resonance imaging. Methods Pathologic diagnosis of rectal adenocarcinoma in 43 cases, preoperative pelvic MRI and IVIM examination. The IVIM parameters were obtained from the IVIM original images with b = 1000s / mm2 by using the three-layer method and the single-layer method to outline the IVR parameters: pure diffusion coefficient (D), perfusion score (f), perfusion-related pseudodiffusion coefficient value. The differences between the two ROI sketches and the normal bowel wall parameters were compared. The ROC curve was used to analyze the value of the ROI sketching method to distinguish the normal bowel wall. Results There was no significant difference in D value, F value and D * between the three-layer method and the single-layer method in mapping ROI of rectal cancer lesions (P> 0.05). Compared with the normal intestinal wall, the values of RO measured by three-layer method and monolayer method were lower (P <0.05), and the f value of single-layer method in mapping rectal cancer lesions was also lower (P < 0.05). Three-tier method of diagnosis accuracy and specificity higher. Conclusion There is no significant difference between the IVIM parameters of rectal cancer lesions using the three-layer method and single-layer method to outline the ROI. The data obtained by the three-layer method have a higher differentiation degree with the normal bowel wall.